There are numerous situations in the mechanical arts where it is necessary to linearly reciprocate a driven member or members in response to the rotary motion of a drive member. One practical approach to converting rotary to linear reciprocating motion is a cam-driven mechanism wherein a cam follower carried by the member to be reciprocated operates in a helical cam track of at least two revolutions, i.e., a 720.degree. helical cam track. Typical applications of such mechanisms are in level wind mechanisms, valve actuators, gun mechanisms, etc. It will be appreciated that, in the case of 720.degree. helical cam tracks, there is necessarily a cam track intersection where the track sidewalls are interrupted. The cam follower must therefore negotiate this track intersection in two different directions without the guidance afforded by the track sidewalls. One approach to ensuring smooth passage through a helical cam track intersection is to make the cam follower oblong or boat-shaped such that it effectively bridges the gaps in the track sidewalls at the intersection. Another approach, as disclosed in commonly assigned Chiabrandy U.S. Pat. No. 4,216,698, is to provide a rotary crossover switch carrying a pair of opposed sidewall segments which are selectively positioned to bridge the track sidewall gaps during cam follower transit of the intersection.
It is accordingly an object of the present invention to provide an improved crossover mechanism for guiding a cam follower through a cam track intersection.
A further object is to provide a crossover mechanism of the above-character wherein complete guidance of the cam follower through the intersection is conveniently and reliably assured.
An additional object is to provide a crossover mechanism of the above-character, wherein smooth transition of the cam follower through the track intersection at high speeds is readily accommodated.
Another object is to provide a crossover mechanism of the above-character wherein complete synchronism of its operation with the movement of the cam follower is accomplished in a simplified manner.
Yet another object is to provide a crossover mechanism of the above-character, which does not resort to special cam follower configurations.
A still further object is to provide a crossover mechanism of the above-character, which is simple and compact in construction, inexpensive to manufacture, and reliable over a long operating life.
Other objects of the invention will in part be obvious and impart appear hereinafter.